As to the OP situation: If he is gone too long (as in weeks) then with a pause in fermentation, the Krausen in the airlock COULD, note I said COULD, become a dried out hard blockage. Then a temp rise might cause fermentation to pick back up and cause a blowout.
I would recommend removing it within a week at the latest and run some hot water through the S type airlock to remove the excess. Refill and replace. Then keep an eye on it.
“Anyone can drink beer, but it takes intelligence to enjoy beer.” — Stephen Beaumont
No more recipies for me. My beer MUST be mine.